Add Extra Validations

Author: mr-zepol

src/main/java/org/cyclonedx/util/serializer/MetadataSerializer.java

@@ -11,7 +11,6 @@
 import org.cyclonedx.Version;
 import org.cyclonedx.model.Metadata;
 import org.cyclonedx.model.Property;
-import org.cyclonedx.model.component.evidence.Occurrence;
 import org.cyclonedx.model.metadata.ToolInformation;
 
 import static org.cyclonedx.util.serializer.SerializerUtils.shouldSerializeField;
@@ -67,7 +66,7 @@ private void createMetadataInfo(
     //Tools
     parseTools(metadata, jsonGenerator);
 
-    if (metadata.getAuthors() != null && shouldSerializeField(metadata, version, "author")) {
+    if (CollectionUtils.isNotEmpty(metadata.getAuthors()) && shouldSerializeField(metadata, version, "author")) {
       if (isXml) {
         ToXmlGenerator xmlGenerator = (ToXmlGenerator) jsonGenerator;
         writeArrayFieldXML(metadata.getAuthors(), xmlGenerator, "author");
@@ -132,18 +131,18 @@ else if (version.getVersion() >= Version.VERSION_15.getVersion()) {
         jsonGenerator.writeFieldName("tools");
         jsonGenerator.writeStartObject();
         if (isXml && jsonGenerator instanceof ToXmlGenerator) {
-          if (choice.getComponents() != null) {
+          if (CollectionUtils.isNotEmpty(choice.getComponents())) {
             writeArrayFieldXML(choice.getComponents(), (ToXmlGenerator) jsonGenerator, "component");
           }
-          if (choice.getServices() != null) {
+          if (CollectionUtils.isNotEmpty(choice.getServices())) {
             writeArrayFieldXML(choice.getServices(), (ToXmlGenerator) jsonGenerator, "service");
           }
         }
         else {
-          if (choice.getComponents() != null) {
+          if (CollectionUtils.isNotEmpty(choice.getComponents())) {
             writeArrayFieldJSON(jsonGenerator, "components", choice.getComponents());
           }
-          if (choice.getServices() != null) {
+          if (CollectionUtils.isNotEmpty(choice.getServices())) {
             writeArrayFieldJSON(jsonGenerator, "services", choice.getServices());
           }
         }

src/test/java/org/cyclonedx/BomJsonGeneratorTest.java

@@ -547,6 +547,18 @@ public void testIssue408Regression_xmlToJson_externalReferenceBom() throws Excep
         assertTrue(parser.isValid(loadedFile, version));
     }
 
+    @Test
+    public void testServicesMetadata() throws Exception {
+        Version version = Version.VERSION_16;
+        Bom bom = createCommonXmlBom("/regression/valid-metadata-tool-no-services.xml");
+
+        BomJsonGenerator generator = BomGeneratorFactory.createJson(version, bom);
+        File loadedFile = writeToFile(generator.toJsonString());
+
+        JsonParser parser = new JsonParser();
+        assertTrue(parser.isValid(loadedFile, version));
+    }
+
     @Test
     public void testIssue562() throws Exception {
         Version version = Version.VERSION_16;

src/test/resources/regression/valid-metadata-tool-no-services.xml

@@ -0,0 +1,19 @@
+<?xml version="1.0"?>
+<bom serialNumber="urn:uuid:3e671687-395b-41f5-a30f-a58921a69b79" version="1" xmlns="http://cyclonedx.org/schema/bom/1.6">
+    <metadata>
+        <tools>
+            <components>
+                <component type="application">
+                    <group>Awesome Vendor</group>
+                    <name>Awesome Tool</name>
+                    <version>9.1.2</version>
+                    <hashes>
+                        <hash alg="SHA-1">25ed8e31b995bb927966616df2a42b979a2717f0</hash>
+                        <hash alg="SHA-256">a74f733635a19aefb1f73e5947cef59cd7440c6952ef0f03d09d974274cbd6df</hash>
+                    </hashes>
+                </component>
+            </components>
+        </tools>
+    </metadata>
+    <components />
+</bom>